Power generation equipment, such as a gas turbine engine, may use a large amount of intake air to support the combustion process. In some instances, the intake air is laden with dust particles, salt, and other types of contaminants, which may damage the compressor blades and other turbine components, via corrosion and erosion, for example. Such component damage may impact the efficiency and performance of the gas turbine engine and may result in more frequent maintenance intervals.
To reduce the problems caused by impure intake air, inlet air filtration units are often used upstream of the compressor. The intake air generally passes through a series of filters and screens to assist in removing the contaminants before they can reach the compressor. Further, the filters and screens may normalize the velocity and pressure of the inlet air flow. The inlet air filtration unit may include an upstream water separation filter for removing water from the inlet (intake) air and one or more downstream filtration modules for removing dust and other impurities.
It has been observed that the number of flying insects (e.g., moths) increases dramatically during monsoon or rainy seasons, which provide damp breeding grounds for such insects. It is common for the flying insects to be drawn toward the lights of the power plant and to be sucked into the compressor's inlet air filtration system, where their ingestion clogs the filters and inhibits the flow of air therethrough. The reduced airflow can cause disruptions to the operation of the gas turbine, which may necessitate the gas turbine being taken off-line for filter cleaning and/or replacement.
To combat this problem, although seasonal and temporary, many power plant operators have installed a large inlet screen with a very fine pore size across the most upstream surface of the inlet air filtration unit (i.e., further upstream of the upstream water separation filter). The inlet screen catches debris, such as insects or bits of paper, and prevents its ultimate ingress into the air filters. Because the inlet screen is a permanent fixture to the inlet air filtration system and must be durable to changing weather conditions, the inlet screen is typically made of stainless steel, which contributes significantly to its cost. In addition to its considerable cost, the inlet screen also results in a pressure drop in the air flow entering the compressor, leading to an undesirable loss in power output for the gas turbine.
It would be useful, therefore, to provide a system to deter insect populations from approaching the inlet air filtration system, thereby eliminating the need for the costly screen and its associated pressure drop, reducing the likelihood of insects being trapped in the air filters, and ensuring the reliable and efficient operation of the gas turbine.